Z-fiducial phantoms allow 3D ultrasound probe calibration with a
single B-scan. One of the main hindrances of using this phantom is
the necessity of segmenting the wires reliably, which requires
human intervention. In this paper, we have shown how we can solve
this problem by mounting a thin rubber membrane on top of the
phantom. The membrane is segmented automatically and the wires can
be easily located as they are at known positions relative to the
membrane. This enables us to segment the wires automatically at
the full PAL frame rate of 25Hz, to produce calibrations in
real-time, while achieving accuracies similar to those reported in
the literature. We also devise a technique to improve the
estimation of the elevational offset by capturing a few images of
the planar membrane. If spatial calibration is known, fully
automatic wire segmentation allows the fiducials to be tracked in
real-time. This also enables temporal calibration to be performed
in real-time as the probe is moved away from the phantom.

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